Advanced Monitoring helps you keep your Plesk installation running smoothly by keeping track of the system resource usage on the server and notifying you when one or more resources’ usage reaches a pre-defined threshold. It works in tandem with the Grafana extension and uses Grafana to display server metrics as graphs and dashboards. The Advanced Monitoring and Grafana extensions are installed in Plesk Obsidian by default.
The reading of disk usage for created domain accounts is available in Tools & Settings > Statistics > Summary Report. The summary report shows the sum of disk space consumption of all subscriptions. You could change the report type to "Full Report" to get the detailed usage reports.